The present invention relates to a robot hand apparatus of an industrial robot.
In recent years, in an automatic assembling process widely carried out, a robot has a plurality of rotatable hands which are sequentially selected in a predetermined order so that many kinds of parts are assembled. Thus, there is a growing demand for the development of a robot hand apparatus having a favorable performance.
A conventional robot hand apparatus is described below with reference to FIG. 5 which is a perspective view showing the conventional robot hand apparatus. A hand base 42 is mounted on a shaft extending from the leading end of a robot 41. The hand base 42 holds a rotary base 43 so that the rotary base 43 rotates at an inclined angle of 45.degree. with respect to a horizontal plane. The rotary base 43 holds a plurality of chucks 44 in the periphery thereof at an angle of 45.degree. with respect to the rotational shaft thereof.
A servo motor 45 is mounted on the hand base 42 and rotates the rotary base 43 through a speed reducing device. A first wire harness 46 is provided between the hand base 42 and the chucks 44. A second harness 47 is provided between the hand base 42 and the power source/control section (not shown) of the robot 41.
The operation of the above conventional robot hand apparatus is described below.
First, the power source/control section outputs a plurality of signals in parallel necessary for controlling the robot hand apparatus. The signals are inputted to the servo motor 45 through the second wire harness 47. In response to the instruction indicated by the signals, the servo motor 45 rotates the rotary base 43 so that the required chuck 44 is set immediately below the rotary base 43. In response to the instruction of the power source/control section through the first wire harness 46, the set chuck 44 starts a predetermined operation. Then, sensors provided on the chuck 44 and in the vicinity thereof feed signals back to the power source/control section via the first wire harness 46 so that the power source/control section controls the chuck 44 in carrying out the predetermined operation. After the operation terminates, the power source/control section outputs signals to the rotary base 43 and the chuck 44 so that a subsequent operation is performed according to instructions indicated by the signals.
As described above, the robot 41 performs a plurality of operations by selecting the required chuck 44.
However, according to the above-described conventional robot hand apparatus, since the first wire harness 46 is positioned between the hand base 42 and the chucks 44, the first wire harness 46 is twisted with the rotation of the rotary base 43. Since it is necessary to twist the first wire harness 46 simultaneously with the rotation of the rotary base 43 in order to rotate the rotary base 43, a great torque is required. The first wire harness 46 is required to be loosened so that the first wire harness 46 follows the rotary motion of the rotary base 43 and is bent. However, there is a possibility that a loosened portion of the first wire harness 46 interferes with other structures, thus causing a trouble in operation or damaging itself or other structures.
It is preferable to accommodate the first wire harness 46 in a structure. But according to the conventional art, a plurality of signals outputted from the power source/control section and a plurality of feedback signals outputted from the sensors pass through a plurality of the first wire harness 46 in parallel, which makes it difficult to accommodate the first wire harnesses 46 in the structure.